Organic fertilizer nitrogen, phosphorus and potassium in chemical analysis methods

Abstract: This paper was determined using chemical analysis of organic fertilizer nitrogen, phosphorus and potassium content, that is, samples were sulfuric acid - hydrogen peroxide digestion, preparation under test solution, sub-taking under test solution with the NC - 2 type fast determination of nitrogen were measured nitrogen, using quinoline phosphomolybdate gravimetric method for determination of phosphorus, and potassium using tetraphenylborate gravimetric determination of potassium, do not need to use the spectrophotometer and flame photometer is suitable for a general compound fertilizer plant used for nitrogen, phosphorus, potassium, respectively more than 011 percent over the sample can be determined by this Law, and method accuracy and precision can meet the production requirements.
Keywords:: organic fertilizer; nitrogen, phosphorus and potassium; chemical analysis method
Organic fertilizer of nitrogen, phosphorus and potassium content in accordance with national industry standards NY525 -2002 requirements, the amount of nitrogen using the whole distillation titration, phosphorus with phosphorus-vanadium-molybdenum yellow spectrophotometry and potassium using flame photometric detection. For general compound fertilizer plant, the first measurement of nitrogen for too long; 2 is because these plants are generally not purchased spectrophotometer and flame photometer, not easy to phosphorus and potassium were determined. In order to address can be analytical determination of organic fertilizer manufacturers of nitrogen, phosphorus and potassium issue, the author summed up in the production practice suitable for manufacturers to use organic fertilizers of nitrogen, phosphorus and potassium Rapid determination of chemical analysis. Point method is to use sulfuric acid - hydrogen peroxide digestion system for taking samples of fluid under test were measured in nitrogen, phosphorus and potassium. Measurement of nitrogen with the NC - 2 Rapid determination of nitrogen-based instrument, to be completed within 10 min in nitrogen distillation, absorption, titration the whole process is fast and accurate characteristics; measured using phosphorus quinoline phosphomolybdate gravimetric method; measured with four K boronic acid potassium weight method. The temperature 120 ℃ under the conditions of the phosphorus and potassium in the sediments along with drying 115 h, can simultaneously determine phosphorus, potassium, greatly reducing the operating time. This method is used in the production practice, and with the national industry-standard methods of analysis the results are basically the same. Common compound fertilizer plants do not need to add analytical instruments, application of this law can be measured organic fertilizer nitrogen, phosphorus and potassium content, to guide
Principles of a method of
Organic fertilizers in sulfuric acid solution, heating, dropping hydrogen peroxide solution, so that the rapid digestion of organic matter, preparation of nitrogen, phosphorus and potassium in liquid under test, and then NC - 2-type fast-setting device measured nitrogen nitrogen, the weight of quinoline phosphomolybdate Determination of phosphorus, potassium tetraphenylborate gravimetric method for determination of potassium.
2. Instrument and reagents
Hydrochloric acid standard solution of 01025 mol / L; mixed indicator agent: Weigh 015 g of bromocresol green and methyl red 011 g dissolved in 100 mL ethanol, using sodium hydroxide solution (about 011 mol / L) and hydrochloric acid solution (approximately 011 mol / L) raised to purple (pH of about 415); neutral boric acid: 20 g / L by adding mixed indicator, using the above-mentioned sodium hydroxide and hydrochloric acid transferred to purple-red. Quinoline-Mo lemon ketone reagents, sodium tetraphenylborate (according reference [4] prepared); NaTPB lotion: A 10-fold diluted with water one-fold solution of sodium tetraphenylborate.
Step 3 Analysis
3.1 Preparation of sample solution under test
Weigh 215000 g samples in 250 mL flask, add 15mL concentrated sulfuric acid, covered with short-necked funnel on the low-temperature furnace heated sulfuric acid white smoke to take a few minutes, the sample after digestion into a black paste to stop heating, remove the small funnel after coolish with a dropper full absorption of hydrogen peroxide, and slowly trickle down from the triangular sides of the bottle until the solution changed from black to colorless far, to continue to cover a small funnel to repeat the above operation, so that complete decomposition of organic matter, and stop by adding hydrogen peroxide, to continue to will be heated to take the low-temperature sulfuric acid solution of white smoke 15 ~ 20 min, cooling, add water to about 75 mL, then cooled, the solution moved into 100 mL flask, fixed volume mixing. The solution of all the dry filtration, the filtrate reserved for measurement of nitrogen, phosphorus and potassium use.
3.2 Determination of Nitrogen
Draw the sample under test liquid 10 mL, as shown in Figure 1 with the NC - 2 type fast determination of nitrogen content of nitrogen was measured. The determination of nitrogen while distilling side instrument used titration method they nitrogen, to be completed within 10 min in nitrogen distillation, absorption, the whole process of titration, and then a second determination of samples do not replace the equipment, is often provided at home and abroad nitrogen to measure the nitrogen, one of the fastest machines. It is water vapor heating method, in an alkaline solution, ammonium nitrogen will be distilled out, without the use of condenser cooling water, using neutral ammonium borate solution absorption. When the absorption solution to absorb ammonia is alkaline, the mixed indicator from purple to blue green, the standard titration with hydrochloric acid solution immediately titrated to maintain the solution is purple (see the specific operation of Reference [1]), while doing a blank test. Samples with nitrogen content of nitrogen (N) the mass fraction of that, according to
Is calculated by:
W (N) = C (V2 - V1) * 0101401 / m * 10 / 100
Where: C - hydrochloric acid solution, the actual concentration of the standard titration, mol / L;
V1 - blank test consumption of hydrochloric acid solution, the volume of the standard titration, mL;
V2 - Determination of sample consumption volume of hydrochloric acid standard solution titration, mL;
m - sample mass, g;
0101401 - Nitrogen of the molar mass, M (N) = 0101401 g / mmol.
3.3 Determination of phosphorus
Draw 25 mL analyte solution in 250 mL beaker, add (11) nitric acid 10 mL, add water to 100 mL, heat to boil, slowly adding 35 mL quinoline-Mo lemon ketone reagent, heating boil 1 min, cooling, use has been constant No. 4 heavy sand core glass crucible filter, clean beaker of water and sediment. The crucible placed in drying oven temperature to 180 ℃ drying 45 min (if the phosphorus and potassium along with determination in the constant temperature drying oven 120 ℃ for 115 h), remove the crucible, cooled in desiccator, weigh. Phosphorus content of samples of phosphorus (P205) of the mass fraction of that determined by the formula:
W (P2O5) = (m1 - m2) * 0103207 / m * 25 / 100
m1 - Quinoline phosphomolybdate precipitation quality, g;
m2 - a blank test quinoline phosphomolybdate obtained the quality, g;
m - sample mass, g;
0103207 - Phosphorus quinoline molybdate quality factor of the quality of converted into phosphorus pentoxide.
Reposted elsewhere in the paper for free download
3.4 Determination of K
Absorb fluid under test 25 mL in 250 mL beaker by adding EDTA solution (400 g / L) 40 mL, by adding phenolphthalein indicator (4g / L ethanol solution) 2 drops, using sodium hydroxide solution (400 g / L) to adjust to the solution, red, and then excess 1 mL, add water to 100 mL, heated to boiling temperature, maintaining 30 min, the heating process of water evaporation under the circumstances, at any time to add water to maintain about 100 mL, remove the cooling, the solution filtered, washed beaker with and precipitation of 3 to 4 times, the filtrate by adding sodium tetraphenylborate (add amount of KOH added per 1 mg of sodium tetraphenylborate solution 015 mL, and had about 7 mL), stir 1min, put it aside for more than 15 min. Would be sediment filter which has been constant weight on the 4th of glass crucible, using sodium tetraphenylborate lotion wash beaker and precipitated 5 ~ 7 times, and finally washed two times. And sediment placed in the crucible of the oven temperature 120 ℃ , dry 115 h, removed placed in desiccator cooling, weighing. Potassium content of samples of potassium (K2O) the mass fraction of that determined by the formula:
W (K2O) = (m1 - m2) * 011314 / m * 25 / 100
m1 - the quality of potassium tetraphenylborate, g;
m2 - a blank tests derived from the quality of potassium tetraphenylborate, g;
m - sample mass, g;
011314 - Four benzene acid potassium hydroxide to convert the quality of the quality factor.
4 Results and Discussion
4.1 Preparation of sample solution under test
This law was determined by chemical analysis of nitrogen, phosphorus, potassium, the relative instrumental analysis methods, said the large amount of samples taken, its high degree of accuracy because of poor uniformity of organic fertilizers, said a small amount of samples taken to measure the reproducibility of the results would be less capable. At the same time sampling can be determined using the same sample under test liquid nitrogen, phosphorus, potassium, with a convenient, fast advantages.
4.2 With regard to nitrogen distillation, absorption, titration
The author in 2000, assembling NC - 2 Rapid determination of nitrogen-based devices, has been a lot of compound fertilizer plant and the analytical testing of the device measured in units of nitrogen, which combines distillation, absorption, titration in one, without condenser (ie, no cooling water ), easy to operate, fast, accurate and can be completed within 10 min in the distillation, absorption, titration of fixed nitrogen entire process.
4.3 With regard to the determination of phosphorus
Law with nitrogen, phosphorus and potassium shared determination of phosphorus liquid under test and improve the speed of analysis. As many of compound fertilizer plant not acquired spectrophotometer, can only adopt Quinoline phosphomolybdate gravimetric method for determination of phosphorus. Gravimetric Determination of Phosphorus accuracy, high precision, relatively low sensitivity of spectrophotometry is just a number, this compound fertilizer plants significantly affected because the sample of more than 011% phosphorus can be determined by this Act, less than 011% not make much sense for manufacturers, from time considered. During phosphorus and potassium measurement, after numerous tests, at 120 ℃ drying time 115 h under the conditions of dry phosphorus and potassium in the sediments, the determination of phosphorus did not affect the results (ie, 45 min and 180 ℃ drying under the conditions of measurement is consistent with the results of phosphorus) can simultaneously phosphorus and potassium measured dry.
4.4 With regard to the determination of potassium
Determination of potassium and is based compound fertilizer plant is generally not equipped with the conditions of the flame photometer, using the weight of potassium tetraphenylborate method. Determination of organic fertilizers in the method of acid-soluble potassium is used, dissolution of metal cations more, although the fluid under test by adding sufficient amount of EDTA solution, when the fluid under test, when transferred to alkaline boil 15 min later, there will be a small amount of hydroxide precipitate produced, but this does not affect the determination of potassium, as long as filters to remove these deposits, and then sodium tetraphenylborate precipitation of potassium, the determination of potassium not affected. This law applies to more than 011% potassium determination of the samples can also be formulated to meet the Fertilizer plant production.
5 results of the analysis comparing
This method has been repeatedly used in the production practice, the results of their analysis is accurate, reliable, suitable for production of compound fertilizer plant to guide formulation, and industry-standard analytical method comparison results of the analysis to measure deviations meet the requirement. Table 1 and Table 2 are measured the same sample (dried crushed to 0115 mm sieve through organic fertilizer) use a different laboratory results of the analysis of this Law and the Law compared with the industry-standard analytical method comparison results of the analysis.
Table 1 of this law results of the analysis of different laboratory comparison (%)
Inspection Unit W (N) W (P2O5) W (K2O)
Yulin Shi Tokutomi Fertilizer Co., Ltd. 1.14 4.10 1.98
Nanning plant protection compound fertilizer plant 1.06 4.13 2.13
Chongzuo lion compound fertilizer plant 1.164.12 2.02
Table 2 of this Act and the industry-standard analytical methods for analysis of contrast (%)
Analysis of W (N) W (P2O5) W (K2O)
Law 1.14 4.10 1.98
NY525 -2002 1.20 4.10 2.10
Note: NY525 -2002 Determination of results of scientific experiments in Yulin City, Center for the determination of the results of tests.
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[2] TAN live. Was measured using rapid determination of nitrogen in the ammonia-nitrogen wastewater [J]. Phosphate & Compound Fertilizer, 2005, 20 (2): 69 - 70.
[3] The People's Republic of China agriculture and industry standards. NY525 1 2002. Organic fertilizer [S].
[4] The People's Republic of China Ministry of Chemical Industry. HGK2843 -1997. Chemical products, chemical analysis used the standard titration solution, standard solution, reagent solution and indicator solution [S].
[5] The People's Republic of China National Standard GB15063 -2001, Fertilizer (Compound Fertilizer) [S]. Reposted elsewhere in the paper for free download


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